The invention relates to a tooling bar like cutter block or a similar elongated tool beam, such as is used for cutting mechanisms for flat materials, particularly in cross-cutters for webs of sheet or paper-like material. If only carried by the machine frame at their ends, such tool beams have between said ends a free, approximately rod-like tool boy which is not supported with respect to the machine frame and which defines a central or rotation axis.
With such tool beams there is often a need for high stiffness or strength values, particularly with regard to bending, torsion, stretching, etc., as well as for a low mass moment or inertia. So that cutter blocks can cut varyingly long portions from a paper web independently of a flight circle circumference of the knife edge, in conjunction with a counterknife, they are greatly accelerated or decelerated for or before each cut and this is more easily possible the lower the mass moment of inertia.
For reducing the mass moment of inertia in the case of relatively high strengths, the cutter block can be assembled from separate components. For example, a jacket of the cutter block can be made from a high-strength materials, which has a much lower specific gravity than steel of, e.g., 7, 5 or 3 kg/m.sup.3 and, e.g., in the same way as a carbon fiber composite, only weights approximately 1550 kg/m.sup.3, but has a much lower modulus of elasticity than steel.
This jacket can be mounted in rotary manner on a fixed axle rod passing through it, or can be provided with journals inserted at its ends, and which are mounted in machine bearings and are optionally made from a material such as steel, which has a higher specific gravity or a higher modulus of elasticity than the jacket material. In the first case the outer rings of ball bearings are connected in non-rotary manner to the inner circumference of the jacket, and in the second case this applies to the engaging journal ends. In both cases these components or inner parts only extend over very short lengths of the outer jacket or part, so that they make little or no contribution to its strength or other functions. The securing of tool or cutting units to such a jacket is problematical if securing members such as screws engage directly in the outer jacket, and do not permit high tightening torques without a risk of being torn out. The manufacture or shaping of the initially plasticized and therefore dimensionally unstable outer part is problematical, because usually a mold core is required, which with increasing length becomes more difficult to remove from the outer part.
Another disadvantage is that pronounced unbalances can occur, if further functional parts, such as tools, e.g., cutting blades or the like are fixed to the through cylindrical outer part and said unbalances can only be compensated by externally positioned counterweights, which one again greatly increases the mass moment of inertia. Finally, in the case of a rotary tool, there is a very unfavourable relationship between the maximum outside width of the tool body and the maximum flight circle diameter of the tool, which is radially far outside the maximum outside width.